<!DOCTYPE html>
<html lang="en">
    <head>
        <meta charset="UTF-8" />
        <meta name="viewport" content="width=device-width, initial-scale=1.0" />
        <title>Document</title>
    </head>
    <body>
        <script>
            let year = prompt("请输入年份");
            if ((year % 4 == 0 && year % 100 != 0) || year % 400 == 0) {
                alert(`${year}年是闰年`);
            } else {
                alert(`${year}年不是闰年`);
            }
        </script>
    </body>
</html>
